1. Field of the Invention
The present invention relates to a building board that has non-flammability and is excellent in designability.
2. Description of the Related Art
Conventional building boards used for forming wall faces of houses include, for instance, ceramic-based siding boards such as wood fiber-reinforced cement boards, fiber-reinforced cement boards, wood cement boards, fiber-reinforced cement-calcium silicate boards, slag gypsum boards and the like, as well as metallic siding boards, ALC boards and the like.
Design is a major concern in such building boards, and thus improvements in designability are ever in demand.
The surface of abase member of such building boards is coated with, for instance, a UV-curable resin or an electron-beam curable resin that is then cured to forma tough topcoat layer on the surface of the board.
For instance, Japanese Patent Application Laid-open No. S61-178484 discloses an inorganic ceramic-based dressing board that comprises an inorganic ceramic-based base member that has been subjected to a filling treatment; on at least one face of the base member, one or various types of coating layer of a resin coating material such as a acrylic urethane resin, an acrylic resin, an epoxy resin or the like; and on the surface thereof, also a UV-curable type ultra-high hardness clear coating film layer 10μ to 300μ thick. The building board of Japanese Patent Laid-open No. S61-178484 has a topcoat layer formed using a UV-curable resin on the surface of a base member, and boasts a mirror surface finish having depth, as well as excellent designability.
However, resistance to fire is also a major concern, and improvements on fireproofing performance are likewise called for. When forming a topcoat layer on the surface a base member using a UV-curable resin, as in Japanese Patent Application Laid-open No. S61-178484, a significant amount of organic solids is present on the surface of the board, and it is difficult to secure non-flammability. This is true also when using electron-beam curable resins.
Some non-flammability can be imparted by reducing the top clear layer on the surface, but doing so prevents the top clear layer from providing a mirror surface finish having depth, and results in poorer designability.